In various industrial fields, some elongate elements must be pulled, at constant speed and tension, for winding/unwinding thereof with respect to a reception member (a drum or cage for example).
This is in particular the case with the elongate elements used in the offshore field, namely cables, hoses, pipelines or umbilicals.
This maneuver is conventionally made by means of a device called a “tensioner”, which provides firstly take-up by clamping a portion of the elongate element and secondly the longitudinal advancement of the latter.
For this purpose, there exist in particular tensioners that comprise a frame equipped with three guide boxes arranged around a passage axis:                a central guide box, which extends over a central plane passing through the passage axis, and        two lateral guide boxes, which are arranged symmetrically with respect to said central plane.        
This tensioner comprises control means that are suitable for controlling firstly a synchronous conveying, in the same direction, of a front strand of various guide boxes and secondly maneuvering means for adjusting an equidistant separation of these front strands of guide boxes with respect to the passage axis.
However, these current tensioners are not entirely satisfactory; in particular, putting the elongate element in the tensioner may prove to be relatively complex and tedious.
In particular, the frame is generally closed in operation in order to withstand the clamping forces. This frame must therefore be openable, in order to facilitate the introduction of the elongate element by a translation maneuver through the openable part of the frame. In addition, the maneuvering means of such tensioners are often relatively complex.